“Willard Dere is a highly distinguished industry leader with deep
clinical development and strategic industry expertise”

Dr. Dere brings to Seres more than two decades of scientific, clinical,
and strategic biopharmaceutical experience. He is currently Professor of
Internal Medicine, Executive Director of Personalized Health, and
Co-director of the Center for Clinical and Translational Sciences at the
University of Utah Health Sciences Center. Previously, Dr. Dere held
several positions at Amgen, including, most recently, Head of Global
Development and Chief Medical Officer. During his career in the
biopharmaceutical industry, Dr. Dere led the clinical development of
numerous approved products in osteoporosis, inflammation, nephrology,
and oncology.

“Willard Dere is a highly distinguished industry leader with deep
clinical development and strategic industry expertise,” said Roger J.
Pomerantz, M.D., President, CEO and Chairman of Seres. “I am extremely
pleased to welcome Willard to the Seres Board during this important
period, where Seres is developing SER-109 as the first Phase 3 stage
microbiome therapeutic candidate and which may be the first ever FDA
approved microbiome drug.”

Dr. Dere commented: “Seres is advancing a promising pipeline of
microbiome product candidates using a highly differentiated scientific
approach. I am eager to contribute to the company’s objective of
bringing the first FDA approved microbiome products to individuals with
serious diseases.”

Biographical Background

Dr. Dere serves as the Professor of Internal Medicine; B. Lue and Hope
S. Bettilyon Presidential Endowed Chair in Internal Medicine for
Diabetes Research, Executive Director of Personalized Health, and
Co-Principal Investigator of the Center for Clinical and Translational
Science at the University of Utah Health Sciences Center. Prior to
re-joining academia in November 2014, Dr. Dere was in the
biopharmaceutical industry for 25 years. He joined Amgen in 2003 where
he held multiple roles including head of global development, and both
corporate and international chief medical officer. He led development of
programs in various therapeutic areas, and retired from Amgen in October
2014. He began his career at Eli Lilly in 1989, and held a number of
different global roles in clinical pharmacology, regulatory affairs, and
both early-stage translational and late-stage clinical research. Dr.
Dere currently serves on the Board of Directors of BioMarin
Pharmaceutical, Ocera Therapeutics, and Radius Health. He earned his
undergraduate and medical degrees at the University of California,
Davis, completed his internal medicine residency training at the
University of Utah, and his postdoctoral training in endocrinology and
metabolism at the University of California, San Francisco.

About Seres Therapeutics

Seres Therapeutics is a leading microbiome therapeutics platform company
developing a novel class of biological drugs that are designed to treat
disease by restoring the function of a dysbiotic microbiome, where the
natural state of bacterial diversity and function is imbalanced. A Phase
3 clinical study with its lead program, SER-109, is ongoing in patients
with multiply recurrent C. difficile infection. Seres’ second
clinical candidate, SER-287, is being evaluated in a Phase 1b study in
patients with mild-to-moderate ulcerative colitis, and the study has
completed enrollment. Seres is also developing SER-262, the first ever
synthetic microbiome therapeutic candidate, in a Phase 1b study in
patients with primary C. difficile infection. For more
information, please visit www.serestherapeutics.com.
Follow us on Twitter @SeresTx.

Forward Looking Statements

This press release contains forward-looking statements within the
meaning of the Private Securities Litigation Reform Act of 1995. All
statements contained in this press release that do not relate to matters
of historical fact should be considered forward-looking statements,
including without limitation statements regarding Seres’ goals and
objectives, the potential impact of Seres’ microbiome therapeutics
platform, expectations regarding Seres’ pipeline, and Dr. Dere’s
potential contribution to Seres.

These forward-looking statements are based on management’s current
expectations. These statements are neither promises nor guarantees, but
involve known and unknown risks, uncertainties and other important
factors that may cause our actual results, performance or achievements
to be materially different from any future results, performance or
achievements expressed or implied by the forward-looking statements,
including, but not limited to, the following: we have incurred
significant losses, are not currently profitable and may never become
profitable; our need for additional funding, which may not be available;
our limited operating history; the unpredictable nature of our early
stage development efforts for marketable drugs; the unproven approach to
therapeutic intervention of our microbiome therapeutics; the lengthy and
expensive process of clinical drug development, which has an uncertain
outcome; potential delays in enrollment of patients which could affect
the receipt of necessary regulatory approvals; potential delays in
regulatory approval, which would impact the ability to commercialize our
product candidates and affect our ability to generate revenue; any fast
track or Breakthrough Therapy designation may not lead to faster
development, regulatory approval or marketing approval; our possible
inability to receive orphan drug designation should we choose to seek
it; our reliance on third parties to conduct our clinical trials and the
potential for those third parties to not perform satisfactorily; our
reliance on third parties to manufacture our product candidates, which
may delay, prevent or impair our development and commercialization
efforts; our lack of experience in manufacturing our product candidates;
the potential failure of our product candidates to be accepted on the
market by the medical community; our lack of experience selling,
marketing and distributing products and our lack of internal capability
to do so; failure to compete successfully against other drug companies;
potential competition from biosimilars; failure to obtain marketing
approval internationally; post-marketing restrictions or withdrawal from
the market; anti-kickback, fraud, abuse, and other healthcare laws and
regulations exposing us to potential criminal sanctions; recently
enacted or future legislation; compliance with environmental, health,
and safety laws and regulations; protection of our proprietary
technology; protection of the confidentiality of our trade secrets;
changes in United States patent law; potential lawsuits for infringement
of third-party intellectual property; our patents being found invalid or
unenforceable; compliance with patent regulations; claims challenging
the inventorship or ownership of our patents and other intellectual
property; claims asserting that we or our employees misappropriated a
third-party’s intellectual property or otherwise claiming ownership of
what we regard as our intellectual property; adequate protection of our
trademarks; ability to attract and retain key executives; difficulties
managing our growth; risks associated with international operations;
potential system failures; the price of our common stock may fluctuate
substantially; our executive officers, directors, and principal
stockholders have the ability to control all matters submitted to the
stockholders; a significant portion of our total outstanding shares are
eligible to be sold into the market; unfavorable or lacking analyst
research or reports; and that we are currently subject to securities
class action litigation. These and other important factors discussed
under the caption “Risk Factors” in our Quarterly Report on Form 10-Q
filed with the Securities and Exchange Commission, or SEC, on May 4,
2017 and our other reports filed with the SEC, could cause actual
results to differ materially from those indicated by the forward-looking
statements made in this press release. Any such forward-looking
statements represent management’s estimates as of the date of this press
release. While we may elect to update such forward-looking statements at
some point in the future, we disclaim any obligation to do so, even if
subsequent events cause our views to change. These forward-looking
statements should not be relied upon as representing our views as of any
date subsequent to the date of this press release.